Rapier loom by Vignesh Dhanabalan

SCHEME OF WEFT
INSERTION
RAPIER WEAVING

Rapier Weaving Machine- Classification
Rapier Loom
Types of
Rapier
Weft Insertion
Principle
Single Double
Dewas Gabler
Flexible TelescopicRigid
Number of
Rapier

RAPIER LOOM
• A rapier loom uses a rapier to pull the weft yarn across the loom.
• It can be a single rapier or double rapier.
• For a single rapier, a long rapier device is required to extend across
the full width of warp.
• For a double rapier loom, two rapiers enter the shed from opposite
sides of the loom and transfer the weft from one rapier head to the
other near the centre of the loom
• The advantage of two rapier system is only 50% of the rapier
movement is utilized in the weft insertion of single rapier loom

• Very light fabrics with 20 GSM to
heavy fabrics with around 850
GSM.
• Rapier machines are widely
used for household textiles
and industrial fabrics.
• Rapier machines are
designed for universal uses
like
– Weave classic Wool, Cotton,
Man-made fibres, fine Silk and
Fancy yarns.

RIGID RAPIER
1
0
 Thin-wall tubes,~ 10 to 15 mm Ø, or hollow bars of rectangular cross section
• Advantages
• They do not require guiding across the warp sheet; the rapier head slides on
the warp, or on the raceboard.
• High mass and rigid construction ensure straight movement of rapier heads.
• A great diversity for both warp and weft threads in yarn count and character.
• Disadvantages
• Large floor space requirement at least twicethe fabric width.
• Half of their movement is wasted.

FLEXIBLE RAPIER
 Tapes of rectangular cross section, 25 x 10 mm, made of spring
steel or plastic.
 They require guiding across the shed especially for larger working
widths.
• The ribbed guide is similar to that used with the gripper projectile
weaving machines
• Directing the flexible-rapier band through a fixed housing on the
loom frame just outside the reed (no guide mounted in the sley)

FLEXIBLE RAPIER
Advantages:
• Less floor space requirement, spatial productivity is higher.
• Flexible rapier band are wound on wheels or placed in a semi- circular channels
when they are withdrawn outside the shed, and the result is wide working widths
up to 5 m.
Disadvantages:
• Guiding system may lead to the end breakages due to knot failure.
• Using fancy yarns in warp direction is almost impossible.
• By eliminating guides, there is the advantage of reducing end- breaks due to knot
failure, and the weaving of fancy yarns becomes much easier because the
obstructions are removed from the warp shed.

TELESCOPIC -RAPIER
1
3
• The disadvantage of the large floor space requirements of rigid rapiers is removed
on weaving machines equipped with telescopic rapiers.
• Space can be saved on this type of rapier drive if a compound rapier operating on
the principle of telescopic expansion is used.
• This system is used on the Vamatex, Versamat loom.
• The main outer body of the rapier is driven by the eccentric, but the inner body is
fastened to a tape at its outer end. The tape is attached to a fixed point on the
loom, and it passes round four pulleys.
• When the rapier is out of the shed, the inner rapier is withdrawn inside the outer
rapier but, as the outer rapier is driven towards the center of the loom, the tape
slides round the rollers so that the inner rapier moves in the same direction at an
even faster rate.

SINGLE RAPIER WEAVING MACHINE
10
 The rigid rapier is a metal or composite bar usually with a circular cross section
 The rapier enters the shed from one side, picks up the tip of the weft yarn on
the other side and passes it across the weaving machine whileretracting
 Single rapier carries the yarn in one way only and half of the rapier movement is wasted
 Rapier length is equal to the width of the weavingmachine
 Requires high mass and rigidity of the rapier - to ensure straight
movement of the rapier head
 Single rapier machines are not popular
Advantage
• Problem of weft transfer does not arise and normal range of fabric can be
woven.
Disadvantage
• One movement of rapier is wasted.
• Loom speed is very slow. The maximum weft insertion rate is 400 m/min

DOUBLE RAPIER WEAVING MACHINE
15
 They may be rigid orflexible.
 Two rapiers enter the shed from the opposite sides and meet at thecenter.
 The double rapier weaving machines are subdividedinto:
• One-sided weft insertion. One rapier is the transmitting rapier the other is the
taker rapier.
• Double-sided weft insertion. Each rapier acts alternately as the giver and the
taker.
 The giver picks up the yarn from the accumulator at one side, brings itto the
center of the shed, transfers it to the second rapier(taker).
 As the taker retracts, carries the yarn to the otherside.
 In a twin-rapier system, two rapiers move together from the same driving
• source, as is necessary in face-to-face (i.e., double-plush) weaving.

TIP AND LOOP TRANSFER SYSTEM
Tip System
• Package is equipped with a spring
loaded tip and is transferred has a
spring loaded clamp
• The tip of the weft yarn is firmly
gripped by the rapier heads during the
entire period of weftinsertion.
• Firmly gripped by the rapier heads.
• spring-loaded clamp presses to
trap the weft.
Loop transfer system
• weft from supply package exhibits a
fork-like opening
• Weft insertion in the form of hairpin.
• Weft yarn is not firmly gripped, merely
threaded round the rapier head.
• extends the yarn in the form of ‘ U’
shape (loop) to the center
• During retraction of the receiving head,
the loop of weft gets unfolded over the
corresponding part of warp shed After
transfer of loop the thread is retracted
to straighten back.

Tip Transfer
• spring-loaded clamp has a cam profile
that meets a fixed point on the loom.
• The possibility of weft breaks at
transfer is minimized.
• There is minimum chance of the
weft’s being pulled out of the receiving
spring.
• Basically for softer and higher english
count yarn
• yarn thickness, its compressibility and
coefficient of yarn-metal friction govern
reliability of tip-to-tip transfer.
Loop transfer
• Both rapier extends to the outside of
the weaving machine, the space
requirement is high
• Transfer of weft yarns at loom centre
thus imposes a severe restriction on
velocity
• Rigorous abrasion during weft transfer
and shed opening.
• suited for rough and robust yarns and
yarn paprameters do not significantly
affect the system.

DEWAS SYSTEM - (TIP TRANSFER)
 Tip to tip weft insertion principle (Tip transfer principle)
 The tip of the weft yarn is firmly gripped by the rapier heads during the entire
period of weftinsertion
 Type of weft transfer at thecenter
• negative transfer: all flexible rapiers
• positive transfer: Dornier rigidrapier (gentle treatment)
 The giver grips the tip of the yarn, brings it to the center and transfer it to the taker
which retracts and carries the yarn to the other side of the weaving machine

RAPIER HEAD FOR DEWAS SYSTEM
 The gripping unit: a fixed point against a spring-loaded clamp presses to trap the
weft.
 The spring-loaded clamp has a cam profile that meets a fixed point on the loom or sley-
mounting. These points open the clamps when the weft is to be picked up or released
outside the selvedge.
 The right-hand head thus traps the weft at A and pulls it through the shed until the rapiers
meet. The thread is then guided round point B and, as the left-hand head withdraws, the
thread is trapped at C and pulled across the loom to complete insertion.
 In some looms, at time of transfer clamping points in the rapier heads are positively
controlled and opened. The possibility of weft breaks at transfer is minimized. Furthermore,
there is no chance of the weft’s being pulled out of the receiving spring.

PRINCIPLE OF GABLER SYSTEM
(LOOP TRANSFER)
 Weft insertion in the form of hairpin – Loop transfer principle
 The weft yarn is not firmly gripped, merely threaded round the rapier head.
 After its transfer at the center, it is straightened as the taker retracts the
shed.
 The giver extends the yarn in the form of ‘ U’ shape (loop) to the centerof the
weavingmachine
 The yarn is then transferred to the taker, which extends the yarn tothe
other side of the weaving machine by straighteningit
 Both rapier extends to the outside of the weaving machine, the space
requirement ishigh

RAPIER HEAD FOR GABLER
SYSTEM
 The weft is nevergripped.
 It is threaded round the cut-out A in the right-hand rapier head.
 As the rapier advances towards the center of the loom, the yarn is
introduced in the form of a hairpin.
 When the two rapier heads meet at the center of the loom, the
smaller left-hand rapier head enters the yarn-carryingright-hand
head.
 The thread atA is passed under the spring-loaded cover guide at B,
and, as the left-hand rapier is withdrawn, it repositions the weft at C.
 The yarn can then slide through the left-hand rapier head as it is
withdrawn so that the hairpin is straightened out.

RAPIER DRIVES
23
• The rapier motion is mechanically linked with the machine motion
• The rapier motion is completely under control, thus the position of the weft yarn
at any instant during picking is exact
• There are various attempts and alternatives to drive the rapier Systems are still
changing to obtain a smooth picking operation at high loom speeds
(acc/dece/acc/dece)
• The rapier drive should ensure a gentle treatment to the weft yarn while it is being
picked up by the giver rapier or while it is being transferred between rapier heads.
• The rapier head acceleration and its speed are important since the type of motion
results in high forces acting in the body of the yarn.
• If the forces exceed acceptable limits, the weft yarn breaks off.
• The unwinding speed of the weft yarn is determined by the rapier movement.

FLEXIBLE RAPIER DRIVE FROM
OSCILLATING SPROCKET
• The teeth of the sprocket pass through holes in a driving
• band.
• The reciprocating movement may be given to the sprocket
by
• a crank arrangement
20

FLEXIBLE RAPIER DRIVE
GROOVED CAM OPERATED
MOTION
25

FLEXIBLE RAPIER DRIVE : CRANK
& RACK OPERATED
MOTION
26

RAPIER DRIVE FROM
ECCENTRIC
27

RAPIER DRIVE FROM
CYCLOIDAL GEARS
28

RAPIER DRIVE : RADIAL CAM
OPERATED MOTION
30

SALIENT FEATURES OF MODERN
RAPIER LOOM
31
1. Loom speed have been achieved upto 700 PPM and WIR of upto
1400 MPM.
2. The drive assemblies are with no back lash and gearings are
made largely redundant. This has reduced vibrations, floor loading
and noise emission.
3. Speed variation within a loom can be achieved by means of
frequency controlled DC or stepping motor.
4. There are electronically coupled individual drives forall the
motions.
5. Starting marks have been prevented because of improvement in
start up and acceleration.
6. Both warp and weft designs can be changed whilst the loomis
running.
7. There are controlled weft tensioners to make optimum weft tension
and give bestperformance.

SALIENT FEATURES CONT…
32
8. The size of rapier heads have been reduced, so that the warp
thread tension also reduced.
9. It is made possible to have automatic repairing of weft breaks.
10. Loom design is made suitable for quick style change(QSC).
11. Versatility of the loom has been increased to weave as many types
of yarns and fabrics.
12. Power consumption has been reduced comparatively when
compared to that on old model.
13. The selvedge waste has been reduced.
14. There is increasein application of double shed weaving technique
for production of flat wovenfabrics.
15. Two-phase weaving has led to a very high production rates even at
low loom speed.
16. Flexibility of the loom has been greatly improved by making iteasy
and quick to changestyle.

SELVEDGE FORMATION IN RAPIER
WEAVING M/C
Leno Selvedge:
Leno selvedge is obtained by binding the wefts with strong
additional threads working in gauze weave and by eliminating
through cutting the protruding weft ends.
33

WEFT INSERTION RATE OR WEFT
VELOCITY
Average velocity, v = distance/time
For Single Rapier
Example:
•A single rapier loom having a reed space of 180 cm
and running at 225 picks/min will not have
excessive velocities if the rapier can be made to
enter the shed at 600 and leave at 3000. Calculate
the average velocity of the rapier and WIR.
35

WEFT INSERTION RATE OR WEFT
VELOCITY
For Double Rapier
Example:
• If we consider a 2.0m double rapier machine
running at 500ppm and 1000m/min WIR with
22%, 6% and 22% respectively acceleration,
dwell, and retardation for each rapier.
calculate the avg. velocity, Max. velocity and
acceleration of rapier.
hints:-
36

WEAVING PRODUCTION
33
• The weaver frequently wants to know the productivity of a weavingmachine
expressed in terms of square meters of fabric produced per hour. (P).
• Fabric production rate of a single-phase weaving machine:
60 x n η
P1 = x ……………..(m/h)
D x 100 100
P2 = P1 x b ............................................ (m2
/h)
Where,
• n is the machine speed in r.p.m.,
• b is the fabric width inm,
• η is the machine efficiency in percent(%),
• D is the pick density per cm(ppc),
• P1 is the productivity of the weaving machine in terms of meters of fabric
produced per hour(m/h).

Rapier loom by Vignesh Dhanabalan

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Rapier loom by Vignesh Dhanabalan